Us: We want to buy the property, fix up the (3) apartments not occupied by her parents to generate rental income.QuestionsMy thoughts are to work out a deal where we purchase the property from her parents without taking a loan from bank.

Regarding borrow's DTI, Chase thinks that this item is not that important.I wonder will my high DTI impact the loan underwriting?

Strategies like living in a duplex or triplex, adding an ADU, or renting by the room can help maximize cash flow while leveraging FHA or VA loans for lower upfront costs.

This would hopefully maintain strong cashflow from the property will providing some capital to use for the next property acquisition. 

The market is ALWAYS changing but I know at this time, seasoned investors are getting 80% LTV on DSCR in the 6% range and 90% of PP/100% of renovation if total loan does not exceed 75% of ARV for FixNFlip loans. =)  

Loan interest is deductible based on it's use-not the asset securing it. 

(Even went beyond the second page of Google.)I have an investor who wants to partner on a deal by providing a loan for the down payment.

in what I just laid out, you'd make monthly payments to the seller just like you would to a bank for 5 years, and then the remaining principal balance of the loan would be due, at which time presumably you would refinance the house into a commercial mortgage and use the proceeds to pay off the seller. 

(DCSR loan?)

If you get a DSCR loan at 75% of the ARV then you could get a loan for $210,000 and only need to leave the amount of closing costs in the deal, let’s say $15,000 with both sets of closing costs and holding costs.